SOURCE: U.S. Department of Commerce, Bureau of Economic Analysis, Industry Economic Accounts, available at http://www.bea.gov/ as of
November 2009 as reported in U.S. Department of Transportation, Research and
Innovative Technology Administration, Bureau of Transportation Statistics, National Transportation Statistics, table 3-1b, available at
http://www.bts.gov/publications/national_transportation_statistics/ as of
January 2010.